docs: def slugify(value, allow_unicode=False):
      """
      Convert to ASCII if 'allow_unicode' is False. Convert spaces to hyphens.
      Remove characters that aren't alphanumerics, underscores, or hyphens.
      Convert to lowercase. Also strip leading and trailing whitespace.
      Copyright: https://docs.djangoproject.com/en/1.9/_modules/django/utils/text/#slugify
      TODO: replace after stopping support for Django 1.8
      """
      value = force_text(value)
      if allow_unicode:
          value = unicodedata.normalize('NFKC', value)
          value = re.sub('[^\w\s-]', '', value, flags=re.U).strip().lower()
          return mark_safe(re.sub('[-\s]+', '-', value, flags=re.U))
      value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore').decode('ascii')
      value = re.sub('[^\w\s-]', '', value).strip().lower()
      return mark_safe(re.sub('[-\s]+', '-', value))